US pauses new patients on Merck's MS drug, shares dive

Berlin: Germany's Merck KGaA said on Wednesday the US Food and Drug Administration (FDA) had paused the initiation of new patients on its multiple sclerosis evobrutinib drug, sending its share price plunging in early trade.

The regulator's decision was in response to laboratory values suggestive of drug-induced liver injury during phase III studies, Merck said, stressing that the two cases identified had been asymptomatic and the patients' liver enzymes had fully normalised after discontinuation of the study medication.

"Merck is working closely with the FDA to establish the best path forward for the benefit of patients in current and future trials with evobrutinib," the company said in a statement.

Merck shares were down five per cent at 0757 GMT on news of the setback, sliding to the bottom of Germany's blue-chip DAX index. The science and technology group must now place on hold the initiation of new evobrutinib patients and halt studies involving patients who have been taking the drug for less than 70 days.

The FDA's decision impacts just two patients. Recruitment for a phase III trial of the drug was already complete with 2,000 participants and an ongoing study is to continue as planned.

It expects to present the first data from that study in the fourth quarter of 2023.